Reflection nebulae NGC 1973-1977. This group of nebulae does not emit any light of its own. Instead it reflects the light from the hot young stars in and around it. Nebulae are enormous clouds of gas and dust. Gravitational collapse of the gas can lead to the formation of stars. This group of nebulae is part of the massive Orion nebula starbirth complex, which lies around 1500 light years from Earth in the constellation Orion.